As a student, you need to prepare for the test by studying the course material by taking the practice tests in a PSAT preparation books and by starting at the beginning of the year you intend to take the test. Most bookstores on a nearby college campus sell the practice guides. They are also available online. Study the material in the book; time yourself on the questions. After you have finished, check your answers in the back of the book. Do not only seek the correct answer but also study the description the book offers about why the answer is correct is right and yours was wrong.
According to the College Board website, the reading section seeks to examine how well you know the definitions of words and how they fit in the sentence as a whole. To prepare for this section, consult your study guide, and place the words the test makers want you to know on index cards. Study them every evening, and have a friend or parent quiz you.
For the reading comprehension section, practice reading several passages and timing yourself on them. If you find yourself reading the selections slowly at the beginning, do not become overly concerned; you will acquire speed as you continue to practice. Once you've read them, answer the questions. If your number of correct answers is low, practice again--this time, using a different passage.
Brush up on basic algebra, geometry, probability, statistics and data analysis, as the Peterson website advises. The questions on this section are not all multiple choice -- there are some answers you must supply yourself, in the "grid-in" sections. For test day, on the ones that are multiple choice, fill in all the answers as there is no penalty for guessing.
The writing part of the test measures your ability to express written ideas using standard English, to notice flaws and to improve sentence structure, according to the College Board website. The best way to prepare for this portion of the exam is to click on the "Practice Now" links on the website. Three sections make up this portion of the test -- identifying sentence errors, improving sentences and improving paragraphs. The first section requires you to be able to point out mistakes in a sentence or indicate the absence thereof. The second group of exercises tests your ability to choose the best form of a portion of a sentence the test makers will underline. The third part of this section will examine your skills in improving the logic and coherence of a faulty passage.